The present invention relates generally to a substrate support having an end effector configured to support thin substrates such as semiconductor wafers, compact discs, glass wafers, and the like. More particularly, the present invention relates to detection technology that is used to detect a position of the end effector.
Semiconductor substrates are often cleaned within a tank of fluid (or a bath) followed by a rinsing process (e.g., by submerging the substrate in rinsing fluid, or by spraying the substrate with rinsing fluid). A substrate support, such as a spin-rinse-dryer (SRD), is typically used to rinse and to dry a substrate.
The substrate support comprises a base and a plurality of mechanisms that are conventionally known as end effectors or grippers (hereinafter referred to as end effectors). Each end effector is coupled to the base and is configured to clamp a properly positioned substrate in place on the substrate support. In order to allow for substrate insertion and extraction, one or more of the end effectors are moveable so as to move between a clamped position wherein a properly positioned substrate is held in place by the end effectors, and an unclamped position wherein a substrate may be extracted from or received by the substrate support. Typically the end effector is biased toward the center of the base so that in the absence of external actuation the end effector assumes the clamped position. To assume the unclamped position, external actuation is applied such that the end effector moves away from the center of the base.
Occasionally, as the external actuation is removed and the end effector moves from the unclamped position toward the clamped position, the end effector may undesirably travel beyond the clamped position. This undesirable position is conventionally referred to as an xe2x80x9cover clampxe2x80x9d position and may occur when a substrate is improperly positioned, or when a substrate is absent.
An improperly positioned substrate may not receive proper processing and may be damaged during rotation of the substrate support or during subsequent transfer therefrom.
Accordingly, there is a need to provide an improved apparatus and method that may detect when the end effector is in the over clamp position.
An inventive substrate support is provided that comprises a sensing system configured to detect when an end effector is in an over clamp position. Specifically, the inventive substrate support comprises a base and at least one moveable end effector coupled to the base and configured to selectively move between a clamped position wherein a properly positioned substrate is held in place by the end effector, and an unclamped position wherein a substrate may be extracted from or received by the substrate support. In one aspect, the sensing system may have a first part coupled to the moveable end effector and a second part coupled to the substrate support""s base. The first part and the second part are positioned such that the sensing system detects when the moveable end effector is in an over clamp position. In a further aspect, the inventive substrate support may be rotatable.
The inventive method comprises providing a base and providing an end effector coupled to the base and configured to selectively move between the clamped position and the unclamped position. The inventive method further comprises detecting when the end effector exhibits an over clamp condition.
The sensing system may comprise various sensors such as an inductive sensor, a through-beam sensor such as a light emitter and a detector, or a pressure sensor, etc. Use of such an over clamp sensor may prevent substrate damage that can result from improper substrate gripping.
Other features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, the appended claims and the accompanying drawings.